Aussie researchers have discovered they can get the notoriously fussy eaters to broaden their diets if they fiddle with the microbes in their digestive systems.

By transplanting poo from one group of koalas to another, they've been able to get the recipients to chow down on a species of eucalypt they previously refused to eat.

More menu options means a lower risk of starvation events, University of Queensland scientist Michaela Blyton says.

Dr Blyton and colleague Ben Moore, from Western Sydney University, began investigating koala poo transplants after 70 per cent of the koala population on Victoria's Cape Otway starved to death in 2013.

There were simply too many animals in the area and collectively they stripped bare all of the manna gum trees they relied on for food.

But even as they starved to death the koalas refused to touch a different eucalypt, the messmate.

That was despite their abundance and the fact some koalas feed exclusively on that particular species.

That got Dr Blyton and Dr Moore wondering if the microbes present in koalas' guts - their microbiomes - limit what eucalypts then can eat.

So they got busy catching wild koalas that only ate manna gum and kept them in temporary captivity.

They then collected droppings from wild koalas that ate messmate, concentrated the microorganisms in them, and fed them to the captive marsupials in capsule form.

The transplants changed the captive koalas' microbiomes, allowing them to eat messmate.

Dr Blyton says its an important finding that could help boost survival rates when koalas have to be relocated.

That's happens quite frequently in Victoria where population booms put traditional food sources under pressure.

"Sometimes koalas do quite well in those translocations and sometimes they don't," Dr Blyton says.

"It could be that in cases where they don't do well, they're just not able to adapt to the change in diet. Potentially, by changing their microbiomes using faecal inoculations, we might be able to improve the success of some of those translocations."

She says faeces transplants could also be used to re-establish microbiomes in the guts of koalas that have been treated with antibotics for diseases such as chlamydia.

The research has been published in the journal Animal Microbiome.

The project also involved the Australian National University, Deakin University and Cape Otway's Conservation Ecology Centre.

Australian Associated Press